Hand-held fluid delivery device with sensors to determine fluid pressure and volume of fluid delivered to intervertebral discs during discography

ABSTRACT

A fluid delivery device is provided for delivering fluid to a target site such as an intervertebral disc during discography. The fluid delivery device includes pressure and volume sensors to determine the pressure and the volume of the fluid delivered to the intervertebral disc. The fluid delivery device is hand-held during use and includes a syringe assembly having a plunger with threads that enables controlled discharge of the fluid from the fluid delivery device by rotating the plunger in a housing of the fluid delivery device. The fluid delivery device may also include a communication module to wirelessly transfer data to an external device outside of a sterile field, while the fluid delivery device is in the sterile field. The fluid delivery device may also include a physiological sensor to monitor involuntary pain responses based on changing physiological parameters such as increases in body temperature or blood pressure.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional PatentApplication Ser. No. 60/685,466, filed May 27, 2005, the advantages anddisclosure of which are hereby incorporated by reference.

FIELD OF THE INVENTION

The present invention generally relates to a fluid delivery device fordelivering fluid to a target site. More specifically, the presentinvention relates to fluid delivery devices for use in medicalprocedures that benefit from monitoring and analyzing fluid pressuresand volumes of fluid delivered to the target site. Examples of suchmedical procedures include, but are not limited to, discography,vertebroplasty, kyphoplasty, general injection of bone cement,angioplasty, and the like.

BACKGROUND OF THE INVENTION

There are a number of medical procedures in which fluid is permanentlyor temporarily delivered to a target site for medical treatment,diagnosis, and/or monitoring. In some of these procedures, medicalprofessionals benefit from knowing the pressure at which the fluid isdelivered to the target site. One such well-known procedure is anangioplasty procedure in which a balloon catheter is inserted into ablocked artery to be treated. Once the balloon catheter is in place, aballoon of the catheter is then inflated and deflated in one or morecycles to open the blocked artery and restore adequate blood flowthrough the artery. In this instance, pressure is monitored to ensurethat the balloon is not under-inflated or over-inflated.

A fluid delivery device that has been found useful in monitoringpressure during an angioplasty is shown in U.S. Pat. No. 5,385,549 toLampropoulus et al. The device of Lampropoulus et al. includes a housingdefining a fluid chamber for storing the fluid and a plunger for slidingin the fluid chamber to discharge the fluid from the fluid chamber tothe balloon catheter. The plunger is threaded such that an engagementmechanism can lock to threads on the plunger to restrict movement of theplunger to solely rotational movement. This provides controlleddischarge of the fluid into the balloon catheter. The device alsoincludes a pressure sensor for sensing a pressure of the fluid in thefluid chamber and a controller in communication with the pressure sensorto determine the value of the pressure in the fluid chamber. A displayis in communication with the controller to display the value of thepressure. In one embodiment, the display may be located on the housing.

Another relatively new procedure that requires the delivery of fluid toa target site for isolating or diagnosing the cause of back pain isdiscography. Back pain can have a variety of causes. One known culpritis damaged or injured intervertebral discs. Intervertebral discs can bebroadly described as fibrocartilage disposed between adjacent vertebraeof the spine. The fibrocartilage acts as a pad and supports the adjacentvertebrae. When an intervertebral disc is damaged or injured, back paincan result at least in part to pressure being applied to theintervertebral disc. Discography can be used to isolate damagedintervertebral discs.

During discography, a needle is inserted into an intervertebral discsuspected of causing the back pain and a contrast medium is injectedinto the disc through the needle. Using fluoroscopy, the physician candetermine whether the contrast medium is properly positioned within thenucleus of the disc to get an idea about the health of the disc. If thedisc is healthy, the contrast medium will stay in the nucleus. If thedisc is damaged or degenerated, the contrast medium can spread easilythroughout the disc. If the disc is ruptured, the contrast medium canactually discharge out of the nucleus. During the procedure, the patientis asked to respond if any pain is experienced, especially pain thatmimics the condition that the patient is complaining of. The patientlets the physician know that there is pain and the level of pain bytelling the physician the amount of pain experienced on a scale of 1 to10.

Early discography procedures only measured a single factor, namely thelevel of pain response of the patient. However, improvements to thisoriginal procedure have been made. For instance, in U.S. patentapplication Publication No. 2004/0193045 to Scarborough et al., a fluiddelivery device is described for use in discography that monitors bothpressure and volume of fluid being delivered to the intervertebral disc.Other prior art devices used in angioplasty procedures, such as thedevice in Lampropoulus et al., only monitor pressure. Scarborough et al.teaches that information regarding both pressure and volume can becorrelated with the pain experienced by the patient to better diagnosethe condition of the disc being evaluated.

The fluid delivery device of Scarborough et al., however, is notdesigned to be lightweight, hand-held, and placed within the sterilefield during use. In fact, the fluid delivery device of Scarborough etal. utilizes a motor-driven plunger (adding weight to the device) todrive the fluid from a fluid chamber to the intervertebral disc.Scarborough et al. also does not provide for the wireless transfer ofdata from the fluid delivery device in the sterile field to an externaldevice outside of the sterile field and Scarborough et al. does notprovide a fluid delivery device that reduces false pain indications,e.g., patients signaling pain when no actual pain is experienced.

Therefore, there remains a need in the art for a lightweight, hand-helddevice that is capable of delivering fluid to a suspect disc whilemonitoring fluid pressure and a volume of the fluid delivered. Finally,there is a need in the art for a fluid delivery device that isconfigured for transmitting data from the fluid delivery device in thesterile field to an external device outside of the sterile field.

SUMMARY OF THE INVENTION AND ADVANTAGES

A fluid delivery device for delivering fluid to an intervertebral discduring a discography procedure is provided. The fluid delivery devicecomprises a housing having a reservoir for storing the fluid. Thehousing has a hand-held portion for grasping by a user. A manuallyactuated pump is disposed in the housing and configured to pump thefluid from the reservoir. The pump includes a manual actuator foractuating the pump. A discography needle is configured for percutaneousinsertion into the intervertebral disc to deliver the fluid from thereservoir to the intervertebral disc during the discography procedure.The discography needle has a length of at least 5 cm and an outerdiameter of 16 gauge or smaller. A pressure sensor senses a pressure ofthe fluid in the reservoir and generates a pressure signal, while avolume sensor senses a volume of the fluid discharged from the reservoirand generates a volume signal. A controller is in communication with thepressure sensor and the volume sensor to receive the pressure and volumesignals. The controller is also configured to output signals indicativeof the pressure and the volume. A display is mounted to the housing andis in communication with the controller to receive the output signalsand display indications of the pressure and the volume simultaneously onthe display during the discography procedure. A battery is disposed inthe housing for actuating the pressure sensor, the volume sensor, thecontroller and the display. The housing, including the reservoir, thepump including the actuator, the pressure sensor, the volume sensor, thecontroller, the display and the battery cumulatively have a weight of1.5 kilograms or less.

In another aspect of the invention, an external module is provided foruse with the fluid delivery device. The external module is spaced fromthe fluid delivery device, outside of the sterile field, and configuredto receive data, e.g., pressure, volume, and time data, from thecontroller of the fluid delivery device (inside the sterile field). Theexternal module is configured to transfer the data to a remoteprocessing station that may be loaded with software to review, monitor,and/or manipulate the data.

In yet another aspect of the present invention, the fluid deliverydevice includes a physiological sensor for sensing a physiologicalparameter of the patient that is largely uncontrollable by the patient.The physiological parameter changes in response to the patient feelingpain to provide an involuntary pain indication. The controller is incommunication with the physiological sensor to determine values of thephysiological parameter and automatically mark a key value of thepressure, volume, and/or time, in response to the value of thephysiological parameter exceeding a predetermined limit that isindicative of a predetermined pain level.

The present invention provides several advantages over the prior art. Byproviding a lightweight, hand-held device capable of monitoring bothpressure and volume, a user can more easily maneuver the device in thesterile field while performing the discography procedure. This alsoenables the user to continuously monitor the pressure and volume valuesdisplayed on the display while performing the procedure. Other aspectsof the present invention including the external module, the capabilityof performing the printing of data collected by the device by a printerthat is wirelessly connected to the device and the physiological sensor,add to the improvement over the prior art.

BRIEF DESCRIPTION OF THE DRAWINGS

Other advantages of the present invention will be readily appreciated,as the same becomes better understood by reference to the followingdetailed description when considered in connection with the accompanyingdrawings wherein:

FIG. 1 is a top perspective view of a fluid delivery device of thepresent invention;

FIG. 2 is an top exploded perspective view of the fluid delivery deviceof FIG. 1;

FIG. 3 is a bottom partial exploded perspective view of the fluiddelivery device of FIG. 1;

FIG. 4 is an exploded perspective view of a syringe assembly of thepresent invention;

FIG. 5 is a side view of a syringe barrel of the syringe assembly;

FIG. 6 is an end view of the syringe barrel;

FIG. 7 is a partial cross-sectional view taken generally along the line7-7 in FIG. 6;

FIG. 8 is a perspective view of an engagement mechanism of the syringeassembly;

FIG. 9 is a top view of the engagement mechanism;

FIG. 10 is a side view of the engagement mechanism;

FIG. 11 is a bottom view of the engagement mechanism;

FIG. 12 is a cross-sectional view of the engagement mechanism takengenerally along the line 12-12 in FIG. 9;

FIG. 13 is a top perspective view of the engagement mechanism seated ina lower casing of the housing in an engaged position;

FIG. 14 is a bottom perspective view of the engagement mechanism in anupper casing of the housing in the engaged position;

FIG. 15 is a perspective view of an alternative engagement mechanism ofthe present invention;

FIGS. 16A and 16B are partial cross-sectional views of the alternativeengagement mechanism of FIG. 15 illustrating engaged and disengagedpositions, respectively;

FIG. 17 is a perspective view of a second alternative engagementmechanism of the present invention;

FIGS. 18A and 18B are partial cross-sectional views of the secondalternative engagement mechanism of FIG. 17 illustrating engaged anddisengaged positions, respectively;

FIG. 19 is an illustration of a display of the fluid delivery device;

FIG. 20 is a perspective view of a pressure sensor with associatedprinted circuit board;

FIG. 21 is a perspective view of a volume sensor with associated printedcircuit board;

FIG. 22 is a front view of the volume sensor illustrating with hiddenlines a contact member of a rotating disc operatively coupled to theplunger;

FIG. 23 is an exploded view of a main electronic assembly of the fluiddelivery device;

FIGS. 24A and 24B are electrical schematics of electronic components ofthe fluid delivery device of FIG. 1;

FIG. 25 is an flow chart illustrating steps carried out by a controllerof the fluid delivery device to measure volume;

FIG. 26 is a perspective view illustrating a printer and an externalmodule for use with the fluid delivery device of the present inventionto transfer data from the fluid delivery device to the printer or aremote processing station through the external module;

FIGS. 27-29 are illustrations of sample data output from the printer;

FIGS. 30A-30D are illustrations of the fluid delivery device being usedto perform a discography;

FIG. 31 is a side view of a manifold for use with the fluid deliverydevice; and

FIGS. 32-34 are examples of alternative uses of the fluid deliverydevice of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Referring to the Figures, wherein like numerals indicate like orcorresponding parts throughout the several views, a fluid deliverydevice for delivering fluid to a target site during a medical procedureis generally shown at 30. The fluid delivery device 30 of the presentinvention is particularly useful in medical procedures in which it isbeneficial to monitor and analyze fluid pressure and a volume of thefluid delivered to the target site. The fluid may be contrast media,bone cement, hydrogel, saline, or other fluid mediums that are deliveredto target sites for medical monitoring, diagnosis, evaluation, and/ortreatment.

Examples of medical procedures in which it may be beneficial to monitorand analyze pressure and volume include, but are not limited to,discography, vertebroplasty, kyphoplasty, general injection of bonecement, angioplasty, and the like. For purposes of illustration, thepresent invention will often be described for use in discography, i.e.,diagnosing disc problems in intervertebral discs. More specifically, thefluid delivery device 30 will be described for use with pressurizedcontrast media to distend a patient's intervertebral disc. The fluiddelivery device 30 displays critical information such as fluid pressureand volume of the fluid delivered, as well as desired informationrelating the patient's to back pain. This information can be stored ordisplayed in various ways and can be recalled, printed, or transferredto other devices as desired.

Referring to FIGS. 1-3, the fluid delivery device 30 includes a housing32 having a lower casing 34 and an upper casing 36 snap-fit to the lowercasing 34 via a plurality of complimentary tabs 38 and notches 40. Asyringe assembly 42 is captured between the upper 36 and lower 34casings. The syringe assembly 42 includes a syringe barrel 44 thatdefines a fluid chamber 46 of the housing 32 to store the fluid to bedelivered to the target site through a tube set 48. The housing 32 ispreferably formed from a plastic material such as polycarbonate (PC),acrylonitrile butadiene styrene (ABS), high impact polystyrene (HIPS),and the like. The material used to form the housing 32 contributes tothe lightweight nature of the fluid delivery device 30. Of course, othermaterials known to those skilled in the art could be used whilemaintaining the lightweight nature of the fluid delivery device 30. Thefluid delivery device 30, as shown in FIG. 1, including the housing 32and all components connected to (except the tube set 48), or internalto, the housing 32 described hereinafter, preferably has an unfilledweight (without fluid) of less than 1.5 kilograms, more preferably lessthan 0.5 kilograms, and most preferably less than 0.3 kilograms.

Referring specifically to FIG. 1, the housing 32 includes a proximal end33 directed generally toward a user of the fluid delivery device 30during use and a distal end 35 directed generally toward a patientduring use. A hand-held portion 50 is disposed between the ends 33, 35.The hand-held portion 50 is configured for being held by the user duringuse. The hand-held portion 50 is further defined as a waist section ofthe housing 32 preferably having a smaller outer perimeter than at theproximal 33 and distal 35 ends. The hand-held portion 50 is dimensionedto be comfortably grasped in the palm of a hand of the user. This freesa second hand of the user to operate the fluid delivery device 30 asdescribed further below. The hand-held portion 50 has a height H fromabout 0.3 to about 8.0 centimeters, more preferably from about 0.8 toabout 5.0 centimeters, and most preferably from about 1.3 to about 3.0centimeters. The hand-held portion 50 has a width W from about 0.3 toabout 10 centimeters, more preferably from about 2.5 to about 8.0centimeters, and most preferably from about 3.8 to about 6.5centimeters. Thus, the hand-held portion 50 has an outer perimeter orgirth that is comfortably sized to fit in the palm of the hand of theuser during use. At least a portion of the syringe assembly 42 passesthrough the hand-held portion 50 to maximize space and minimize weightof the fluid delivery device 30.

Referring to FIGS. 2 and 4, the syringe assembly 42 is shown in moredetail. In one embodiment, the syringe barrel 44 (preferably formed ofplastic) has a volumetric capacity of 20 mL. It should be appreciatedthat other volumetric capacities could also be used depending on theparticular procedure for which the fluid delivery device 30 is utilized.The syringe barrel 44 includes a nose section 43 at a distal end forpositioning in an opening 45 in the lower casing 34. A threaded fitting49 connects the tube set 48 to a tip of the nose section 43 to providefluid communication between the fluid chamber 46 and the tube set 48.

The syringe assembly 42 also includes a plunger 52 having a distal end53 disposed in the fluid chamber 46 for discharging the fluid from thefluid chamber 46 toward the target site as the plunger 52 moves in thefluid chamber 46 relative to the housing 32. The distal end 53 is fittedwith an elastomeric seal member 51 to seal the distal end 53 in thefluid chamber 46 to prevent fluid from escaping out of the fluid chamber46 past the distal end 53 of the plunger 52. The plunger 52 includesthreads 54 disposed axially along a shaft 55 of the plunger 52. Thethreads 54 allow the user to carefully control movement of the plunger52 within the housing 32 to discharge the fluid by rotating the plunger52 relative to the housing. A handle 57 (or other manual actuator) isoperatively coupled (preferably fixed) to a proximal end of the plunger52 to facilitate grasping by the second hand of the user to move theplunger 52.

Engagement Mechanism

Referring to FIGS. 4 and 8-13, an engagement mechanism 56 controlsoperation of the plunger 52. The engagement mechanism 56 is supported bythe housing 32 to engage the threads 54 of the plunger 52 in an engagedposition E to allow only rotational advancement or retraction of theplunger 52 in the fluid chamber 46. The engagement mechanism 56 can alsodisengage from the threads 54 in a disengaged position D to allowslidable advancement or retraction of the plunger 52 in the fluidchamber 46. The engagement mechanism 56 includes a slide member 58 thatis movable between the engaged E and disengaged D positions to lock tothe threads 54 of the plunger 52 in the engaged position E and disengagefrom the threads 54 in the disengaged position D. The engaged anddisengaged positions are best shown by the hidden lines E and D,respectively, in FIG. 12.

Referring to FIGS. 8-12, a toggle 60 is fixed to the slide member 58 andis configured for actuation by the user to move or slide the slidemember 58 with a thumb and/or forefinger between the engaged anddisengaged positions. The slide member 58 defines an opening 62 forreceiving the threads 54 of the plunger 52. The slide member 58 includescontrol threads 64 extending into a first portion of the opening 62 toengage the threads 54 of the plunger 52 in the engaged position and theslide member 58 lacks control threads 64 in a second, opposite portionof the opening 62 to allow the threads 54 on the plunger 52 to freelyslide through the opening 62 in the disengaged position. The slidemember 58, including the integrally formed toggle 60, is preferablyformed from a plastic material such as polycarbonate, acrylonitrilebutadiene styrene (ABS), high impact polystyrene (HIPS), delrin, nylonand the like. The plastic material used to form the slide member 58contributes to the lightweight nature of the fluid delivery device 30.

Referring to FIG. 13, the slide member 58 is supported in a slide path63 defined between two parallel side walls 61 disposed in the lowercasing 34. The slide member 58 is slidable in the slide path 63 betweenthe engaged E and disengaged D positions. The upper casing 36 (notincluded in FIG. 13) holds the slide member 58 from displacing out fromthe slide path 63 when actuated.

Referring specifically to FIGS. 13 and 14, a restraining mechanism 66 isoperable with the engagement mechanism 56 to restrain the slide member58 in each of the engaged E and disengaged D positions as the slidemember 58 is moved between the engaged E and disengaged D positions.Whether the slide member 58 engages the threads 54 on the plunger 52 isa discretionary choice by the user. However, with the restrainingmechanism 66, once the slide member 58 is in place, the restrainingmechanism 66 keeps the slide member 58 in either the engaged E ordisengaged D position until the user determines that the slide member 58should be moved.

Referring specifically to FIG. 14, the restraining mechanism 66 includesa first detent 68 mounted to the slide member 58 and a first detentpocket 70 for receiving the first detent 68 when the first detent 68moves with the slide member 58 from the disengaged position D to theengaged position E. The first detent 68 is preferably integrally formedwith the slide member 58 and includes an elongated, flexible member 72spaced from a main body of the slide member 58 such that the flexiblemember 72 can flex relative to the main body. The first detent 68 alsoincludes a projection 76 or bump approximately centered on the flexiblemember 72. The upper casing 36 of the housing 32 includes a first detentrail 78 defining the first detent pocket 70 and having a first rampsection 80. The projection 76 of the first detent 68 slides along thefirst detent rail 78 and over the first ramp section 80 to the firstdetent pocket 70 when the slide member 58 moves from the disengagedposition D to the engaged position E.

The restraining mechanism 66 also includes a second detent 68, which isa mirror image of the first detent 68, mounted to the slide member 58and opposed from the first detent 68 and a second detent pocket 70 forreceiving the second detent 68 when the second detent 68 moves with theslide member 58 from the disengaged position D to the engaged positionE. The lower casing 34 of the housing 32 includes a second detent rail78 defining the second detent pocket 70 and having a second ramp section80, the second detent 68 being slidable along the second detent rail 78and over the second ramp section 80 to the second detent pocket 70 whenthe slide member 58 moves from the disengaged position D to the engagedposition E. The slide member 58 is shown in the engaged position E inFIG. 14.

Referring to FIGS. 15, 16A, and 16B, an alternative engagement mechanism156 and restraining mechanism is shown. In this embodiment, the slidemember 58 is replaced by a control switch 82 having a spring-loaded pawl84 that is adapted to snap over a boss 86 when the control switch 82 ispivoted about a pivot axis by the user between the engaged (FIG. 16A)and disengaged (FIG. 16B) positions. The spring-loaded pawl 84 acts asthe restraining mechanism in this embodiment to maintain the controlswitch 82 in either position when moved. The control switch 82 hascontrol threads 164 that are adapted to engage the threads 54 on theplunger 52 in the engaged position and disengage from the threads 54 inthe disengaged position. The control switch 82 is pivotally supportedabout the pivot axis in the upper casing 36 of the housing 32.

Referring to FIGS. 17, 18A, and 18B, a second alternative of theengagement mechanism 256 is shown. In this embodiment, the slide member58 is replaced by an axially movable control member 88 that controls apair of detent arms 90 having control threads 264. The control member 88has pins 92 that engage slots 94 in the detent arms 90. The detent arms90 have a connecting ring 96 or any other connecting method known tothose of ordinary skill in the art to mount the detent arms 90 to thesyringe assembly 42 about the threads 54 of the plunger 52. Each of thearms 90 has a head portion with control threads 264 that mate with thethreads 54 on the plunger 52. The control member 88 can be moved axiallyforward and backward (proximally and distally) with respect to thehousing 32 to force the detent arms 90 into engagement with the threads54 or to allow the control threads 264 to move away from the threads 54of the plunger 52. The detent arms 90 are biased in the engaged positionin this embodiment. As will be appreciated by those of ordinary skill inthe art, additional engagement mechanisms for switching between theengaged and disengaged positions could also be contemplated.

Control System

Referring to FIGS. 19-25, a control system of the fluid delivery device30 is shown. The control system includes a display 100, a plurality ofinput devices 112, 114, 115, 116, 118, 120, 168, a controller 104 (e.g.,microcontroller with microprocessor, memory, and other associatedcomponents), a pressure sensor 106 for sensing a pressure of the fluidin the fluid chamber 46, and a volume sensor 108 for sensing a volume ofthe fluid discharged from the fluid chamber 46.

The controller 104 is in communication with the pressure sensor 106 andthe volume sensor 108 to determine values of the pressure and the volumeof the fluid delivered to the target site, and the display 100 is incommunication with the controller 104 such that the controller 104 caninstruct the display 100 to display the determined values of pressureand volume simultaneously. The memory is used to save data during useincluding data relating to pressure, volume, and time. The controller104 is configured for automatically saving key procedure data in thememory such as a maximum pressure reached during the procedure, amaximum volume discharged during the procedure, zeroed pressure, zeroedvolume, and a maximum time. It should be understood that the memoryinternal to controller 104 is able to store data regarding the fluidinjected into a plurality of individual discs during the course of asingle procedure. Thus, each time the device is used to inject contrastmedia into a single disc 186, defined below as an “event,” thecontroller memory stores data describing the volume of media injected,the pressure at which the media is injected and the points associatedwith the different levels of pain sensed by the patient.

Referring specifically to FIGS. 1 and 19, the display 100 is mountedbetween the upper and lower casings 36, 34 of the housing 32 at thedistal end. More specifically, the display 100 is mounted at aproximally facing angle relative to a longitudinal dimension of thehousing 32 to provide easy viewing by the user. The display 100 isconfigured to indicate a total pressure (e.g., total gauge pressure) ofthe fluid in the fluid chamber 46, a differential pressure of the fluid,a volume of the fluid discharged from the fluid chamber 46, a currentevent being monitored, e.g., disc 1 . . . disc 8, etc., a total timethat pressure has been applied during that event (in some embodiments,the timer is not triggered until the total pressure exceeds apredetermined threshold such as 0.5 psi), and a total number of key datapoints recorded during that event. The display 100 also has a number oficons that indicate different operations of the fluid delivery device 30such as a RCL icon that indicates previously recorded data has beenrecalled, and a printer icon that indicates data is being wirelesslytransmitted to an external device such as a printer 160.

The plurality of input devices 112, 114, 115, 116, 118, 120, 168, alsoreferred to as buttons or switches 112, 114, 115, 116, 118, 120, 168,are disposed beneath the display 100 on a keypad 110 (see FIG. 2). Thekeypad 110 protrudes into an opening in the upper casing 36 foractuation by the user during use. These selectable buttons or switches112, 114, 115, 116, 118, 120, 168 are in communication with thecontroller 104 to carry out different operations of the fluid deliverydevice 30 when pressed by the user, as set forth below.

A volume tare switch 112 is configured to reset the value of themeasured volume to zero upon actuation. The controller 104 is configuredto display the reset or differential volume on the display 100. In someinstances, it may be beneficial to display a volumetric flow rate on thedisplay 100 in addition to the volume of the fluid discharged. This willallow the user to determine whether the fluid is being delivered to thetarget site, e.g., intervertebral disc, at a constant or variable rate.In some, but not all versions of the invention, the volume flow ratedata are displayed as status bars 178 on the display.

A pressure tare switch 114 is configured to reset the value of thepressure to zero upon actuation to provide a differential pressure. Whenthe pressure tare switch 114 is actuated, the controller 104 causes thedisplay 100 to show both the total pressure, and a differentialpressure. This “differential pressure” is the difference between totalpressure and the pressure that was measured when switch 114 is actuated.As stated above, the display 100 always shows the total gauge pressure,which cannot be zeroed. During use, as the pressure continues toincrease after the pressure tare switch 114 has been actuated, thedisplay 100 then shows the increased pressure (differential pressure),while the display 100 continues to show the total gauge pressure. Thus,the controller 104 is configured to simultaneously display thedifferential pressure and the total pressure on the display 100 wherethe total pressure is based on a total value of the pressure unaffectedby actuation of the selectable pressure tare switch 114. Both pressurevalues can be displayed in units of kPa or psi, changeable by pressing aunit switch 115. Alternative presentations of pressure can be in otherunits, BAR or ATM, for example.

A key data switch 116 is configured for marking key values of the dataupon actuation. The controller 104 is configured to save the key valuesin the memory of the controller 104. In the disclosed embodiment of thepresent invention, the controller 104 automatically saves pressure(differential and total gauge), volume, and time data during theprocedure. Additionally, key values of this data can be marked manuallyfor each disc by pressing the key data switch 116. This allows the userto manually mark the pressure, volume, and time data at a specific pointin the procedure. For example, the user may mark the data when thepatient indicates that a certain pain threshold has been met, i.e.,based on pain responses from the patient. The display 100 indicates thenumber of key data points that have been manually saved for the fluidinjection process performed on each disc.

A new event switch 118, e.g., a next disc button, allows the user tosegregate the data for different events, e.g., different discs that areevaluated. In other words, the controller 104 is configured to correlateseparate data to each of a plurality of monitoring events, or discs inthe case of discography. The total pressure, differential pressure,volume, and time may be reset to zero when the new event switch 118 ispressed so that new data for each new event is recorded. In anyprocedure, the physician can decide to move to a different event or discfor evaluation. In the event a different disc is selected, the physiciancan press the new event switch 118 to indicate that a different disc hasbeen chosen. In one embodiment of the fluid delivery device 30, the usercan name the specific disc by tabbing through various pre-installed discnames. The display 100 indicates that a different disc has been chosen.

An on/recall switch 120 is configured for turning the fluid deliverydevice 30 on to begin use or to recall the data saved during use. Thecontroller 104 is configured such that once some data has been saved inthe memory, upon actuation of the on/recall switch 120, the controller104 selectively displays the data saved for each event, including thekey values of the data saved for each key data point of each event savedduring the procedure. Therefore, the on/recall switch 120 allows theuser to access the saved data (manually saved data & automatically saveddata) during the procedure and without requiring printing. The data isdisplayed on the display 100 while being recalled. The recalled datascrolls automatically or manually depending on how the user presses theon/recall switch 120. When the user presses and holds the on/recallswitch 120, scrolling is automatic. Otherwise, each press of theon/recall switch 120 manually advances to the next key data point or tothe next saved event. The on/recall switch 120 can, for example, scrollthrough maximum pressure, maximum volume, zeroed pressure, key datavalues for multiple key data points, for each disc. The display 100indicates what data is currently being shown when in the recall mode. Itis understood that the “on” and “recall” functionality of the on/recallswitch 120 could be separated into two different switches.

Referring to FIG. 23, a main printed circuit board (PCB) 122 of thecontrol system is shown. The main PCB 122 carries one or more batteries124. The fluid delivery device 30 is preferably cordless such that thebatteries 124 provide all of the power needed by the fluid deliverydevice 30 and the communications connection to the final data storagedevice is wireless. The fluid delivery device 30 is also configured toconserve battery power by providing a power down mode after apredetermined time period, described further below. The main PCB 122also includes connectors 126 for receiving connecting ends 128 of cables130 used to electronically couple electronic components on the main PCB122. The pressure sensor 106 and associated components are disposed on asecond PCB 132, which is electrically coupled to the main PCB 122. Thevolume sensor 108 and associated components are disposed on a third PCB134, which is electrically coupled to the main PCB 122. The second PCB132 and the third PCB 134 also include connectors 126 for receiving aconnecting end 128 of cables 130 interconnecting the second PCB 132 andthe third PCB 134 to the main PCB 122.

The display 100 is shown mounted in a cage 136. The cage 136 snap-fitsto the main PCB 122 via corresponding snap-fit connectors 138 andnotches 139. A spacer 140 and elastomeric mounts 142 can be used tosecure the display 100, preferably a LCD display 100, in the cage 136.

Referring to FIG. 20, the pressure sensor 106 is shown in more detail.The pressure sensor 106 is mounted to the second PCB 132. The connector126 on the second PCB 132 is used to place the pressure sensor 106 incommunication with the controller 104 of the control system such thatthe controller 104 can determine values of pressure based on controlsignals from the pressure sensor 106. In the preferred embodiment, thepressure sensor 106 is a Honeywell 26PCFFS2G electronic pressure sensor106 with a pressure sensing frequency of once every 147 mS.

Referring briefly to FIG. 7, the pressure sensor 106 is shown fitted tothe syringe barrel 44. The pressure sensor 106 has a hub 107 fit into areceiving pocket 109 on the syringe barrel 44. The hub 107 is sealed inthe receiving pocket 109 to prevent fluid from leaking out of the fluidchamber 46 around the pressure sensor 106. The hub 107 may also be fixedin the receiving pocket 109 with an adhesive, snap-fit connection, orthe like. The pressure sensor 106 senses the pressure in the fluidchamber 46 through a sensing orifice 111 that is in communication withthe fluid chamber 46 via a passage 113. Other methods of placing thepressure sensor 106 in contact with the fluid in the fluid chamber 46could also be contemplated. As will be appreciated by those of ordinaryskill in the art, other electronic sensors or methods of sensingpressure could be used. Also, it should be appreciated that since thepressure sensor 106 is in direct fluid communication with the fluidchamber 46, the measured pressure is the pressure of the fluid in thefluid chamber 46.

Referring to FIGS. 21 and 22, the preferred embodiment of the volumesensor 108 is shown. In this embodiment, the volume of the fluiddischarged from the fluid chamber 46 is measured by detecting rotationof the plunger 52 relative to the housing 32. In this embodiment, thevolume sensor 108 includes a contact member 146 (shown by hidden linesin FIG. 22) coupled to the shaft 55 of the plunger 52 to rotate with theplunger 52 during the rotational advancement of the plunger 52. Thecontact member 146 is mounted to a rotating disc 148 (shown by hiddenlines in FIG. 22) fixed about the plunger 52 by two tabs 147 that ridein grooves 149 defined in the shaft 55 of the plunger 52. Spring washersor bushings 151 having slightly wavy and flexible undulations are usedto rotatably mount the rotating disc 148 in an annular shoulder pocket153 defined in an open proximal end of the syringe barrel 44. The springwashers 151 hold the rotating disc 148 tightly against the third PCB134, as the rotating disc 148 rotates relative to the third PCB 134.

The volume sensor 108 further includes a plurality of sensing members150 a, 150 b, 150 c, 150 d fixed to the third PCB 134. The controller104 measures the volume by sensing a rotational position of the contactmember 146 relative to the sensing members 150 a, 150 b, 150 c, 150 d asthe contact member 146 rotates with the plunger 52. In essence, thecontact member 146 completes a circuit between any two of the sensingmembers 150 a, 150 b, 150 c, 150 d when simultaneously contacting anytwo of the sensing members 150 a, 150 b, 150 c, 150 d. The controller104 is configured, as described further below in reference to FIGS. 24A,24B, and 25, to determine the rotational position of the contact member146 when the contact member 146 is in contact with any two of thesensing members 150 a, 150 b, 150 c, 150 d. The controller 104 is alsocapable of determining whether the plunger 52 is rotating clockwise todischarge the fluid (adding an incremental volume amount to the totalvolume measured) or if the plunger 52 is rotating counterclockwise,which backs-off fluid delivery (subtracting an incremental volume amountfrom the total volume measured).

Accuracy of volume measurement can be increased by increasing the numberof sensing members 150 a, 150 b, 150 c, 150 d mounted to the third PCB134. In the embodiment shown, four sensing members 150 a, 150 b, 150 c,150 d are used to determine the volume. Thus, in the instance in whichthe plunger 52 discharges 0.5 cc or mL with every full rotation of theplunger 52, the best resolution of the volume sensor 108 is 0.125 cc ormL. In other words, the controller 104 is capable of identifying thecontact member 146 at four positions for each full revolution.

As pressure increases, the volume measurement may be obscured by changesin shape of the seal member 51 of the plunger 52, or other compressiblecomponents. Likewise, the presence of air bubbles in the fluid mayaffect volume measurement. Thus, the controller 104 may be programmed tonominally account for such changes in volume based on a predeterminedadjustment factor.

In an alternative embodiment (not shown), the volume is determined by acircuit board with three switches mounted to the circuit board under theshaft 55 of the plunger 52. Two of the switches click against notchescut in the threads 54 every 36 degrees. The third switch senses if theslide member 58 is in the disengaged position in order to set the volumereading to zero when the threads 54 are disengaged. Two more switchescould be added to the circuit board to sense translation and achieve areading in the disengaged position.

In yet another alternative embodiment (see FIG. 15), the volume isdetermined with the use of a plastic cage 200 that travels with theshaft 55 of the plunger 52, but does not rotate. Sides of the plasticcage 200 are encoded with indentations 202 every 0.01 inches. An LED 204shines on the indentations 202. An optical sensor 206 reads thereflections off the plastic surface and sends a corresponding signalback to the controller 104. The controller 104 then counts the number ofindentations 202 sensed to determine volume (each indentation 202corresponds to a predetermined amount of fluid delivered).

FIGS. 24A and 24B, when assembled together, form a block and partialschematic diagram of the electronics integral with the fluid deliverydevice 30. The controller 104, in one version of the invention is anAtmel ATmega3290/V 8-bit Microcontroller with in system programmablememory available from the Atmel Corporation of San Jose, Calif. Thisparticular controller 104, in addition to a CPU, has a 32 k byte flashmemory, a 1 k byte EEPROM and 2 k bytes of RAM. Collectively, thesememories as depicted as a single memory block 249 in FIG. 24B. A crystal105 provides a clock signal to the controller 104. In one version ofthis invention, this signal is at a frequency of 3.6864 Hz. Thiscontroller 104 is also capable of driving a set of 4×40 LCD segments. InFIG. 24B, a bus 250 is shown connecting the controller 104 to thedisplay 100. The display 100 preferably has a screen refresh rate of 350mS or less.

Power to actuate the display 100, the controller 104, the pressuresensor 106, the volume sensor 108, and an LED 156 for transmitting datawirelessly to external devices (described further below), comes from twoseries connected batteries 124, called out with a single identificationnumber. In one version of the invention the CR2016 lithium button cellbattery available from Renata SA, Itingen/Switzerland are employed asthe batteries 124. These batteries have an output potential (each cell)of 3 volts. The output potential across the batteries 124 is applied toa voltage regulator 254 to produce a constant DC voltage. In one versionof the invention the FAN2500 100 mA CMOS LDO Regulator available fromFairchild Semiconductor of South Portland, Me., is employed as thevoltage regulator 254.

The positive terminal of the series connected batteries 124 is appliedto the VIN and Enable pins of the voltage regulator 254 through a FET252. As long as the device remains off, there is no path to ground fromthe positive terminal of batteries 124. Consequently, there is novoltage drop across resistor 256. Since the voltages across the sourceand gate of FET 252 are equal, the FET is normally in the off state.This construction thus means that, as long as the fluid delivery device30 is not actuated, there is only a nominal parasitic current flow outof the batteries 124. This current is in typically 100 nanoAmps or less.Consequently, over an extended period of time, the charge stored in thebatteries does not deplete to the level below which the batteries are nolonger able to actuate the power consuming components internal to thefluid delivery device 30. Thus, this power conserving circuitry allowsthe fluid delivery device 30 of this invention to remain stored andready for use with the original batteries 124 for a period of time ofoften more than 6 months and, in some instances, 12 months or more.

The 3 VDC output signal produced by the voltage regulator 254 is outputthrough the output pin. A capacitor 258, tied between the output andground, filters the AC component from the output signal. Also in FIG.24A is shown a capacitor 260 tied between the bypass pin of the voltageregulator 254 and ground. The capacitor 260 is provided to minimize thenoise of the 3 VDC signal output by the voltage regulator 254. Theactual adjustment of the output voltage of the voltage regulator 254 maybe fixed at manufacture. Thus the need to provide voltage adjustmentresistors is eliminated. FIG. 24A does illustrate the connection betweenthe ground pin of the voltage regulator 254 and ground.

In FIGS. 24A and 24B, the application of the 3 VDC as the VCC signal tothe controller 104 is shown as the A-A connection. To reduce drawingcomplexity, the rail along which the 3 VDC signal is available to othercomponents is not shown.

Also seen in FIG. 24A are two series connected resistors 261 and 262connected between the input pin of the voltage regulator 254 and ground.The voltage present at the junction of the resistors 261 and 262 isproportional to the potential across the batteries 124. The voltage atthis junction is applied to the controller 104. As part of the controlsequence, the controller 104 periodically compares this voltage to areference voltage level. If the comparison indicates that the batterypotential is below the reference level, the controller 104 asserts a lowbattery warning that is integral with display 100.

As discussed above, normally FET 252 is turned off so as to preventcurrent flow to the voltage regulator 254. Consequently, normally thecontroller 104 and the other components internal to the fluid deliverydevice 30 are in the off mode in which they do not draw charge from thebatteries 124. The fluid delivery device 30 is turned on for use bydepressing the on/recall switch 120. The on/recall switch 120 is anormally open push button switch tied between the gate of FET 252 andground. In FIG. 24A, a diode 264 is located between the gate of FET 252and the on/recall switch 120 wherein the cathode of the diode isdirected towards the on/recall switch. The closing of the on/recallswitch 120 ties the gate of FET 252 to ground. This zeroing out of thegate voltage turns FET 252 on so as to allow current flow to the VIN andEnable pins of the voltage regulator 254. The voltage regulator 254, inturn, outputs the 3 VDC signal. The application of the 3 VDC signal tothe controller 104 as the VCC causes the actuation of the initializationmodule internal to the controller 104 so that the controller 104 turnsitself on.

Shown connected across the diode 264 and the on/recall switch 120 is anormally off FET 266. The controller 104 applies a control signal to thegate of FET 266. This control signal is asserted as part of theinitialization of the controller 104. This turning on of FET 266 thusties the gate of FET 262 to ground once the fluid delivery device 30 isfirst turned on. Also seen in the Figures is a resistor 268 tied betweenthe gate of FET 266 and ground.

While not illustrated, it should be understood that a software modulerunning on the controller 104 is a time out monitor. If the controller104 does not detect a change in the signals from one of the otherdevices connected thereto such as the pressure sensor 106, the volumesensor 108 or another one of 112, 114, 115, 116, 118 and 168 inputdevices (switches), the time out monitor initiates an internal programto save the recorded data and power down the fluid delivery device 30.In some versions of the invention, this power down process is initiatedif the device has been inactive for a time period that may be set to beanywhere from 2 to 5 minutes; 3 minutes being common. The last part ofthis process is the negation of the control signal to FET 266. Thenegation of this control signal causes FET 252 to return to its normallyoff state so as to prevent further draining of the charge stored in thebatteries 124.

Collectively, because there is only parasitic depletion of the chargestored in the batteries 124 when the device is in deactivated storage,and the time out monitor deactivates the fluid delivery device 30 aftera period on non use only the relatively small sized batteries arerequired. The small size and weight of the batteries contributes to theminimization of the overall size and weight of the fluid delivery device30.

Input devices 112, 114, 115, 116, 118 and 168 are depicted in FIG. 24Aas a set of normally open switches. Each switch (device) has one endtied to ground. The opposed ends of the switches are tied to separatepins of the controller 104. In the Figures this connection isestablished over a bus 269. A voltage source internal to the controller104 (source not illustrated) applies a logical HIGH signal to eachdevice (switch) internal to the controller 104. When any particulardevice (switch) is momentarily depressed, (switch closed) the signalpresent at the associated controller pin is pulled to ground. Thus alogical LOW signal is sensed at the pin when the associated switch isclosed.

Also shown as a switch tied between a pin of controller 104 and groundis engagement detector 152. When the engagement mechanism 56 is in theengaged state, the switch of engagement detector 152 is closed. Thispulls the signal present at the associated pin of controller 104 LOW.Based on the assertion of this LOW signal, a processing module internalto the controller allows the processing module that generates volumedata to execute and output volume measurement data.

The pressure sensor 106 is schematically depicted in FIG. 24A. Asdescribed above, the 26PCFFS2G±100 psi Gage/Vacuum Gage Sensor fromHoneywell Sensing and Control, Freeport, Ill., functions as the pressuresensor 106. This particular pressure sensor 106 includes apiezo-resistive sensing element. The pressure sensor 106 itself isconstructed as a Wheatstone bridge. The 3 VDC signal is applied to thepressure sensor 106. The opposed end of the pressure sensor 106 is tiedto ground. The potentials across the resistive elements of the pressuresensor 106 are applied to the opposed IN+ and IN− input pins of adifferential input ΔΣ analog to digital converter (ADC) 270. One suchADC 270 is the LTC2433-1 ADC available from Linear Technologies ofMilpitas, Calif. As also seen in the Figures, the ground point of thepressure sensor 106 is tied to the REF input pin of the ADC 270.

This particular ADC 270, outputs a digitized representation in thedifference between the voltages across the opposed ends of sensor 106 asa serial bit stream. This data stream is output with a clock signal. InFIG. 31B these signals are shown as being applied to the controller 104over a multi-wire bus 272.

The volume sensor 108 is also schematically illustrated in FIG. 24A. Thefour sensing members 150 are depicted as contacts 150 a, 150 b, 150 cand 150 d. The contact member 146 is shown as a wiper that rotates andthat can electrically connect any two of the adjacent contacts. Contact150 a is tied to ground. The 3 VDC signal is applied to contact 150 bthrough a resistor 274. The signal present at the junction of contact150 b and resistor 274 is applied to an input pin of the controller 104.In the Figures, this signal is shown as being applied to controller 104through a conductive path that is part of bus 276. The 3 VDC is alsoapplied to contact 150 c through a resistor 278. The signal present atthe junction of contact 150 c and resistor 278 is applied back to aninput pin of controller 104 through a second conductor integral with bus278. Contact 150 d is also tied to a pin of controller 104.

Referring to FIGS. 24A and 25, the controller 104 is configured toperiodically perform illustrated steps 302-318 to carry out volumemeasurement. In essence, the volume measurement sequence is carried outby the controller 104 by sequentially checking signals at the controller104. In a first step 302, the controller 104 determines whether thecontact member 146 is at a first rotational position that electricallyconnects contact 150 a and contact 150 b by detecting the signal at theinput pin of the controller 104 corresponding to contact 150 b. If thecontact member 146 is in this first rotational position, across contacts150 a and 150 b, then the signal present at the input pin will be drawnto ground by contact 150 a. The controller 104 will recognize this asindicating that the contact member 146 is across contacts 150 a and 150b. From here, the controller 104 will proceed to determine whether thetotal volume should be increased or decreased in steps 312-318(described below).

If the contact member 146 is not at this first rotational position, thenthe signal at the input pin corresponding to contact 150 b will remainHIGH and the controller 104 will move to the second step 304. In thesecond step 304, the controller 104 next determines whether the contactmember 146 is at a second rotational position that electrically connectscontact 150 a and contact 150 c by detecting the signal at the input pincorresponding to contact 150 c. This second step 304 is carried out inprecisely the same manner as the first step 302.

If the contact member 146 is not at this second rotational position,across contact 150 a and contact 150 c, then the controller 104internally pulls contact 150 d to ground in a third step 306. Then, in afourth step 308, the controller 104 again checks the signal at the inputpin corresponding to contact 150 b to look for the same type of effectlooked for in the first step 302, i.e., the signal present at the inputpin is pulled to ground. If so, then the contact member 146 is at athird rotational position, across contact 150 b and contact 150 d. Ifnot, then the controller 104 moves to a fifth step 310 to check thesignal at the input pin corresponding to contact 150 c to look for thesame type of effect looked for in the second step 304, i.e., the signalpresent at the input pin is pulled to ground. If so, then the contactmember 146 is at a fourth rotational position, across contact 150 c andcontact 150 d.

If the controller 104 does not detect that that the contact member 146is at any of the four rotational positions, then the contact member 146is determined to be at a neutral position (between rotational positions,not in contact with any two of the contacts 150 a, 150 b, 150 c, 150 d)and the volume measurement sequence is restarted at start 300. If thecontact member 146 is detected at any one of the rotational positionsacross two adjacent contacts 150 a, 150 b, 150 c, 150 d, and a currentrotational position of the contact member 146 has changed from apreviously detected rotational position (see step 312), then thecontroller 104 either adds (contact member 146 has shifted onerotational position clockwise) or subtracts (contact member 146 hasshifted one rotational position counterclockwise) an incremental volumevalue (here 0.125 mL) to a total measured value displayed on the display100. This is shown in steps 314-318. The controller 104 is configured tocarry out the volume sensing sequence once every 555 μs. In other words,volume measurement is preferably not carried out continuously.

IR transmitting LED 156 is actuated by the controller 104. As seen inFIG. 24B, the LED 156 is connected to the source of FET 282. The drainof FET 282 is connected to the 3 VDC rail. The 3VDC signal is alsoapplied to the gate of FET 282 through a resistor 283. The gate of FET282 is also tied to a pin of the controller 104. The cathode of the LED156 is tied to ground through two series connected resistors 284 and286. A capacitor 288 is tied between the 3 VDC rail and the junction ofresistors 284 and 286.

Normally, the current present at the gate of FET 282 holds FET in thenon-conducting state. The controller 104 actuates the LED 156 by tyingthe gate of FET 282 to ground, connection not shown. This results in theturning on of FET 282 so there is current flow there through. When FET282 is turned on, the charge stored across capacitor 288 flows throughthe FET 282 so as to increase the current flow through the LED 156. Thisreduces the power the batteries 124 need to provide in order to energizethe LED 156.

Referring back to FIG. 4, an engagement detector 152 is in communicationwith the controller 104 and responsive to the engagement mechanism 56 todetect when the engagement mechanism 56 is in the engaged position E,i.e., the plunger 52 can only be advanced via rotation. The controller104 is configured to measure the volume of the fluid delivered from thefluid chamber 46 only when the engagement mechanism 56 is in the engagedposition E. When the engagement detector 152 indicates that theengagement mechanism 56 is in the engaged position E, volume measurementis carried out and the volume delivered is displayed on the display 100.When the engagement detector 152 indicates that the engagement mechanism56 is in the disengaged position D, volume measurement discontinues andthe volume delivered is not shown on the display 100.

In other embodiments, the engagement detector 152 is a reed switch (notshown) that senses a magnet (not shown) in the slide member 58 when thethreads 54 are disengaged. In some embodiments, the controller 104resets the volume each time the slide member 58 moves from the engagedposition back to the disengaged position.

Data Transfer

In some embodiments, the fluid delivery device 30 includes acommunication module 154 (see FIG. 23) supported on the main PCB 122.The communication module 154 is in communication with the controller 104to communicate the stored data from the controller 104 to an externaldevice such as a printer 160 or external module 162, as shown in FIG.26. The communication module 154 preferably includes a wirelesstransmitter 156 (see FIG. 26) for wirelessly transmitting the data fromthe controller 104. In the embodiment shown, the wireless transmitter156 is the IR-transmitting LED 156 operating under principles ofinfrared communication. Of course, communication with the printer 160 orexternal module 162 can take many known variations. Communication can bewireless using standard methods such as IR or RF.

When communicating with the printer 160 or the external module 162, datais compressed or encrypted prior to being sent to the printer 160 or theexternal module 162. The printer 160 or external module 162 then expandsthe data and puts it into the desired format for printing or for furtherdata transfer. This method serves to minimize the transmission betweenthe fluid delivery device 30 and the printer 160 or the external module162. It also saves memory space on the controller 104. Both the printer160 and external module 162 include a wireless receiver 158, 159 (IRsensor in one embodiment) for receiving the data from the wirelesstransmitter 156. The external module 162 may include a microprocessorwith memory for receiving, processing, and temporarily storing the datareceived from the fluid delivery device 30. More preferably, theexternal module 162 is configured to process the data from thecommunication module 154 into a form usable by a remote processingstation 166, such as a computer electronically connected to the externalmodule 162 using a USB cable or other electronic coupling methods.Software is loaded on the remote processing station 166 to view,monitor, or manipulate the data received from the fluid delivery device30 via the external module 162.

In use, the fluid delivery device 30 (preferably a sterilized, singleuse item) is placed in a sterile field. The external module 162 (andprinter 160) is placed outside of the sterile field (shown by theboundary S). The external module 162 then receives the data from thefluid delivery device 30 when the user presses a data transfer switch168 on the keypad 110. This method of use is particularly advantageousduring medical procedures to keep the external module 162 outside of thesterile field and eliminate the need to sterilize such devices. Itshould be appreciated that the data could be directly transferred to theremote processing station 166 from the fluid delivery device 30 in theevent the remote processing station 166 is internally equipped with adevice similar to the external module 162.

The fluid delivery device 30 could also be configured for communicatingwith a docking station (not shown) to download data to the printer 160,or to a jump drive through a USB port, etc. Communication with thedocking station can be through electrical contacts or near fieldcommunication such as RF, IR, or inductive coupling.

When the data is transferred to the printer 160 (by also selecting thedata transfer switch 168 or another switch on the keypad 110), the datacan be represented in a table 174 or graphical format 170, 172. Samplesof the various tables 174 and graphs 170, 172 that can be used are shownin FIGS. 27-29. The data that is represented on the printouts caninclude manually and automatically saved data, e.g., data from key datapoints for each event, and/or automatically saved data such as maximumpressure, maximum volume, maximum time, zeroed pressure, and zeroedvolume.

Print results can include, for example, a pressure vs. time graph 170, avolume vs. time graph (not shown); a pressure vs. volume graph 172; atable 174 of manually and automatically saved data; marked locations 176of saved key data points on the graph (see points 1, 2, and 3), and aseparate printout specific to an event or disc number so that separatetables and graphs can be obtained for each event or disc evaluated. Inthe disclosed embodiment, each graph has the same scale on separate axesso the results can be easily compared.

In one embodiment, the pressure, volume, and/or time can be correlatedto one metric, such as a slope, for quicker and easier reading andevaluation by a physician. The controller 104 is configured to determinethis composite metric based on the pressure, volume, and time, or anycombination of at least two of these parameters. The controller 104could also display the composite metric on the display 100 such as bystatus bars 178 that gradually fill to indicate a rise in value of thecomposite metric (see FIG. 19). In one embodiment, the composite metricis the value of the pressure divided by the value of the volume. Inanother embodiment, the composite metric is the value of the volumedivided by the value of the time. In other embodiments, the compositemetric is the change is pressure divided by the change in volume or thechange in volume divided by the change in pressure. It should beappreciated that other variations for the composite metric could also becontemplated.

Discography and Pain Detection

Referring to FIGS. 30A-30C, the fluid delivery device 30 is shown foruse in discography. In discography, an introducer needle 180 is firstplaced percutaneously in the intervertebral disc 182 to be evaluated. Ahandle 181 is fixed to a proximal end of the introducer needle 180 toassist the user in placing the introducer needle 180 in the disc 182.FIG. 30A illustrates inserting the introducer needle 180 in the disc182. In the embodiment shown, a stylet 184 is used to insert theintroducer needle 180 into the disc 182 and place a distal end of theintroducer needle 180 at a nucleus 186 of the disc 182. A cap 190 isfixed to a proximal end of the stylet 184. The cap 190 may be configuredto lock to the handle 181 of the introducer needle 180 to facilitateinsertion of the introducer needle 180 in the disc 182. The cap 190 maylock to a luer connector 183 and the handle 181 in the manner shown inU.S. Patent Application Publication No. 2004/0127814 to Negroni, whichis hereby incorporated by reference. FIG. 30B illustrates the introducerneedle 180 placed in the disc 182 with the stylet 184 being removed andFIG. 30C illustrates the connection of a threaded luer-lock connector191 of the tube set 48 to the luer-lock connector 183 to allow the fluidto be delivered from the fluid delivery device 30 to the introducerneedle 180.

Referring to FIG. 30D, in an alternative method, the introducer needle180 is first percutaneously placed adjacent to the disc 182 withoutpenetrating the disc 182. A separate delivery needle 185 is theninserted (with a separate delivery needle stylet, not shown) in theintroducer needle 180 to penetrate the disc 182. FIG. 30D illustratesthe delivery needle 185 in place after the delivery needle stylet (notshown) has been removed from the delivery needle 185. Once a distal endof the delivery needle 185 is properly positioned in the disc 182, asshown in FIG. 30D, the threaded luer-lock connector 191 of the tube set48 is connected to a luer-lock connector 187 on a handle 189 fixed tothe delivery needle 185. The handles 181, 189 could be locked togetherin the manner shown in U.S. patent application Publication No.2004/0127814 to Negroni, which is hereby incorporated by reference. Insome embodiments, a 3-way valve is used with the tube set 48 to controlfilling of the fluid chamber 46 and delivery of the fluid from the fluidchamber 46 to the delivery needle 185. Regardless of the methodutilized, the introducer needle 180, when used alone (FIGS. 30A-30C), orwith the delivery needle 185, referred to collectively as discographyneedles, preferably have an outside diameter of 16 gauge or smaller,e.g., 18 gauge or smaller, or even 20 gauge or smaller, etc., and alength of 5 cm or longer. Some discography needles 180, 185 have anoutside diameter of 18 gauge or smaller and/or a length of 12 cm orlonger. Alternative introducer needles that do not include handles mayalternatively be employed.

During use in discography, the plunger 52 forces the fluid from thefluid delivery device 30 into and though the discography needle 180, 185to the disc 182. The fluid chamber 46 of the fluid delivery device 30preferably contains a contrast media. The contrast media is a fluid thatis opaque to x-rays and thus provides an image of the interior structureof the patient's disc 182 in x-ray photographs or under fluoroscopy. Thecontrast media is pressurized by turning the handle 57 of the plunger 52to rotate the plunger 52. The plunger 52 then moves in the fluid chamber46 of the syringe barrel 44. When the plunger 52 moves in the fluidchamber 46, the fluid is pressurized and forced from the discographyneedle 180, 185 into the disc 182. The pressure within the syringebarrel 44 increases as the fluid fills the disc space. If there is aproblem with the disc 182, the patient will experience pain. Or, in theevent that there is a rupture in the disc 182, the patient may notexperience pain, but the amount of fluid injected without a resultantincrease in pressure will indicate a rupture. In discography, the fluiddelivery device 30, its plunger, is preferably configured to deliver thefluid at a maximum pressure of up to 180 psi and in some versions up to200 psi. The controller 104 may activate an alarm, either audible orvisual, when the pressure exceeds a predetermined limit or limits. Inone version of the invention, an alarm module executed by controller 104continually monitors the total pressure of the fluid discharged by thedevice. When this pressure exceeds 100 psi, this module causes both thetotal and differential pressure presentations on the display to flash.When the total pressure exceeds 120 psi, the alarm module asserts outputsignals that causes both pressure presentations to display a HI messageto the user.

During discography, the user may desire to accurately measure the amountof pain experienced by the patient. As discussed in the background, thepatient typically calls out the amount of pain based upon a scale of 1to 10. To better ensure diagnosis, more accurate methods of measuringpain are needed. Applicants have developed several methods that can beused in conjunction either directly, i.e. actually feeding directly intothe fluid delivery device 30, or indirectly, i.e., physician input basedupon the information generated from the patient.

One method would be to allow the patient to enter a pain magnituderesponse by, for example, squeezing a bulb (not shown). This would beconsidered a voluntary pain response, or a response that that patientis, to some extent, capable of controlling. The amount of pressureapplied by the patient to the bulb would be registered and recorded inthe fluid delivery device 30 as well as being displayed on the fluiddelivery device 30. For example, the readout may be in the form of amoving graph that shows the level of pain, i.e., the amount of pressureapplied to the bulb by the patient, as a spike on the graph or a lightindicator with varying colors, change of the backlight color, or astatus bar of pain indication, etc.

Another method would be the collection of unsolicited pain responsesfrom a patient based on changes in physiological parameters such as bodytemperature, blood pressure, muscle flex, heart rate, respiration,oxygen saturation, integumentary system, muscle tone, intracranialpressure, pupil size, vagal nerve tone, hormonal release, metabolicchanges, brain waves, and the like. These are involuntary pain responsesthat are largely uncontrollable by the patient thereby reducing falsepain indications, as opposed to the squeeze bulb embodiment describedabove, which could result in false pain indications. This data would beeither individually displayed, or displayed as a pain magnitude basedupon a pre-determined pain magnitude scale corresponding to specificdata. The display types would be similar to those discussed above withthe physical action, i.e., bulb squeezing by the patient.

In this embodiment, a physiological sensor 192 is used to monitor thechanges in the physiological parameters. The physiological sensor 192 isplaced in communication with the controller 104 for sensing thephysiological parameter of the patient, e.g., body temperature, bloodpressure, muscle flex, etc. Thus, the physiological sensor 192 may beone or more of a blood pressure sensor, a body temperature sensor, amuscle displacement sensor, etc. A plurality of physiological parameterscould be monitored at the same time with multiple physiological sensors192 with pain indicated when a combination of changes is detected. Thepain magnitude could also be correlated to a predetermined algorithmutilizing these parameters.

The controller 104 is configured to automatically mark key values of thepressure, volume, and time in response to the physiological parameter(s)exceeding a predetermined limit, i.e., without the need for thephysician to press the save button. Values of the physiologicalparameter(s) or corresponding pain magnitude can be displayed, saved,and printed vs. pressure, volume, and/or time. In this embodiment, thecontroller 104 is configured to display the value of the physiologicalparameter on the display 100. These values can also be highlighted onthe printouts for ease of reading.

In some embodiments, referring to FIG. 31, a manifold 194 can be used tosplit the fluid delivered from the fluid delivery device 30 intomultiple tube sets 48. In this embodiment, the manifold 194 includes aninlet 196 in fluid communication with the fluid chamber 46 and aplurality of outlets 198 for directing the fluid to multiple discographyneedles 180, 185. By using a stopcock (shown as a valve in FIG. 31), anynumber of the discography needles 180, 185 can be shut-off from fluiddelivery such that the fluid is delivered to only one discography needle180, 185 at a time. The patient may also remain unaware of which disc182 the fluid is being delivered to, thus better isolating the disccausing the patient's back pain and reducing false pain indications fromthe patient.

As discussed above, the fluid delivery device 30 is sized to allow auser to hold it in single hand. Given the relatively light weight of thedevice the user can hold it in his/her hand for an extended period oftime without tremor-inducing fatigue developing in either the hand orsupporting arm. Furthermore, since the pressure and volume informationare presented on the device, the user does not have to divert his or hereyes to a remote display in order to view these parameters.Collectively, this means the user can focus his/her mental effort on themore important aspects of the procedure: manipulating the handle;monitoring the pressure and volume of fluid being delivered; and theresponse of the patient.

Other Uses

The fluid delivery device 30 of the present invention may also beutilized in other procedures in which the measurement of both pressureand volume in a lightweight, hand-held device may be useful. Examples ofsuch procedures include vertebroplasty, kyphoplasty, and angioplasty.For illustration purposes, the use of the fluid delivery device 30 invertebroplasty, kyphoplasty, and angioplasty is shown in FIGS. 32-34,respectively.

Referring to FIG. 32, in vertebroplasty, an introducer needle 300 isplaced in a vertebral body 302 using the technique previously describedwith respect to discography. More specifically, a distal end 304 of theintroducer needle 300 is placed inside the vertebral body 302 at atarget site. The fluid delivery device 30 is then connected to aproximal end 306 of the introducer needle 300 via the threaded luer-lockconnector 191. In this case, the fluid delivered may be a flowablematerial capable of setting to a hardened condition such as PMMA bonecement, hydrogel, or the like. The introducer needle 300 used forvertebroplasty preferably has an outer diameter of 13 gauge or larger.

Referring to FIG. 33, in kyphoplasty, an inflatable member 400 ispositioned in the vertebral body 302 through an access cannula 402 usingmethods well known to those skilled in the art. The inflatable member400 is connected to a distal end of an inflation catheter 404. The fluiddelivery device 30 is connected to a proximal end of the inflationcatheter 404 by the threaded luer-lock connector 191 to provide fluidcommunication between the fluid delivery device 30 and the inflatablemember 400 to inject the fluid (such as contrast media) into theinflatable member 400. The inflatable member 400 may be a balloon thatexpands as fluid is delivered, under pressure, into the inflatablemember 400. In this procedure, the fluid delivery device 30 ispreferably configured to deliver the fluid into the inflatable member400 at pressures of 300 psi or greater, more preferably at pressures offrom 300 to 450 psi. The access cannula used to provide access to thevertebral body 302 for the inflatable member 400 preferably has an outerdiameter of 13 gauge or larger.

Referring to FIG. 34, in angioplasty, an inflation catheter 500 with aballoon 502 at a distal end thereof is placed in a partially blockedblood vessel 504 at a lesion 506 to compress the lesion 506 and improveblood flow in the vicinity of the lesion 506. The fluid delivery device30 of the present invention is connected to a proximal end of theinflation catheter 500 to provide fluid communication between the fluiddelivery device 30 and the balloon 502 to inject the fluid into theballoon 500. In this procedure, the fluid delivery device 30 ispreferably configured to deliver the fluid into the balloon 500 atpressures of 300 psi or less, more preferably at pressures of 200 psi orless, and most preferably at pressures of 175 psi or less.

The illustrated and disclosed handle 57 is understood to be illustrativeand not limiting of the types of manual actuators that may be used toactuate the plunger 52. For example, a rotating knob that drives ageared shaft may perform this function. Also a lever assembly may beused in still other versions of this invention.

Similarly, the shape of the housing 32 is again understood to beexemplary, not exclusionary. In an alternative construction of theinvention, the housing is generally pistol shaped. In this version ofthe invention, the fluid chamber and plunger are located in the barrelsection. The manual actuator may take the form of a lever assemblywherein the lever arm extends forward from the handgrip portion of thehousing in a manner similar to a trigger. In this version of theinvention, the display may be a section of the housing that extendsupwardly at an angle from the barrel section. Likewise, the position ofthe batteries within the housing may change from what has beendescribed.

Likewise this invention is not limited to delivery devices wherein aplunger contained in the fluid chamber provides the motive force forpumping the fluid out of the chamber. In alternative versions of theinvention, other pumping devices may be used to force the fluid throughthe introducer needle 180. Thus, in one potential alternative version ofthe invention, the pump may be a bellows pump. Either gravity or suctionpressure causes the fluid in the fluid chamber (fluid reservoir) to flowinto the pump. In a compression cycle, the fluid is forced through theintroducer needle 180.

From the above description it should likewise be clear that alternativetransducers may be used to monitor the pressure or volume of the fluidapplied to the target site (disc 182, vertebral body 302, or catheterballoon 502). For example, in the above described version of theinvention, capacitance sensing may be used to monitor plunger rotation.In this version of the invention, the capacitance between a fixed plateor plates and a plate or plates that rotate with the plunger may bemonitored to provide an inferential indication of plunger extension andretraction. Alternatively, a Hall sensor that monitors a magnet attachedto the moving head of the pump assembly may be used to monitor theextension and retraction of the pump head. Alternatively a transducerthat varies capacitance as a consequence of plunger or pump headdisplacement may be used to provide a measure of fluid displacement.Again the monitoring of this movement would provide an inferentialmeasure of the volume of fluid pumped to the target site. A volumesensor with a mechanical transducer such as a paddle wheel may even beemployed. Likewise there is no requirement that, in all versions of theinvention, the transducer employed to monitor fluid pressure be apiezo-resistive unit. This unit may be formed from piezoelectricmaterial. In some versions of the invention a diaphragm type sensor maybe employed as the pressure sensor.

Similarly, the disclosed circuit is understood to not be the solepossible circuit of this invention. Components different than thedisclosed circuit may be employed. For example, in some versions of theinvention there may be a processor and one or more separate memorychips.

Furthermore, in alternative versions of the invention, the wirelesscommunications module may both transmit and receive signals. This may beuseful so that the static device used to receive the data collected inthe procedure returns an acknowledgement that the data are received.Also, during manufacturing, calibration information may be sent to thedevice for storage in the controller memory 249.

Obviously, other modifications and variations of the present inventionare possible in light of the above teachings. The invention may bepracticed otherwise than as specifically described within the scope ofthe appended claims.

1. A fluid delivery device for delivering fluid to an intervertebraldisc through a fluid conduit during a discography procedure andmonitoring selected parameters of the fluid delivered to theintervertebral disc, said device comprising: a housing including areservoir for storing the fluid, said housing having a hand-heldportion; a manually actuated pump disposed in said housing andconfigured to pump fluid from said reservoir, said pump including amanual actuator; a discography needle connected to said housing forreceiving the fluid discharged by said pump, said discography needleshaped for percutaneous insertion into the intervertebral disc to directthe fluid into the intervertebral disc and having a length of at least 5cm and an outer diameter of 16 gauge or smaller; a pressure sensordisposed in said housing and positioned to sense the pressure of thefluid discharged by said pump, said pressure sensor producing a pressuresignal representative of the sensed pressure; a volume sensor disposedin said housing for sensing a volume of the fluid discharged by saidpump, said volume sensor producing a volume signal representative of thevolume of fluid discharged by said pump; a controller disposed in saidhousing and connected to said pressure sensor for receiving the pressuresignal and to said volume sensor for receiving the volume signal, saidcontroller configured to: based on the volume signal, determine thecumulative volume of fluid discharged by said pump; and output signalsrepresentative of the pressure and volume of the fluid discharged bysaid pump; a display mounted to said housing and in communication withsaid controller for receiving the output signals representative of thepressure and volume of discharged fluid, said display configured to,based on said controller output signals, display indications of thepressure and volume of fluid discharged by said pump; and a batterydisposed in said housing for actuating said pressure sensor, said volumesensor, said controller and said display, wherein said housing,including said reservoir, said pump including said actuator, saidpressure sensor, said volume sensor, said controller, said display andsaid battery cumulatively have a weight of 1.5 kilograms or less.
 2. Thedevice as set forth in claim 1, including a selectable volume tareswitch attached to said housing and in communication with saidcontroller and configured for resetting said value of the volume to zeroupon actuation, so that said controller generates an output signalindicating the volume of fluid discharged by said pump after theresetting operation.
 3. The device as set forth in claim 1, wherein saidpump is a plunger that is mounted to said housing and has a headdisposed in said reservoir.
 4. The device as set forth in claim 3,wherein: said plunger is formed with external threads; an engagementmechanism is mounted to said housing for engaging said threads of saidplunger in an engaged position to allow rotational advancement of saidplunger in said reservoir and for disengaging from said threads in adisengaged position to allow slidable advancement of said plunger insaid reservoir.
 5. The device as set forth in claim 3, wherein saidvolume sensor includes a contact member operatively coupled to saidplunger for rotating with said plunger relative to said housing duringsaid rotational advancement and a plurality of sensing members fixedrelative to said plunger such that the volume is measured based on saidcontact member being sensed by said plurality of sensing members as saidcontact member rotates with said plunger relative to said plurality ofsensing members.
 6. The device as set forth in claim 3, including anengagement detector in communication with said controller and responsiveto said engagement mechanism to detect when said engagement mechanism isin said engaged position such that said controller measures the volumeonly when said engagement mechanism is in said engaged position.
 7. Thedevice as set forth in claim 1, including a selectable recall switchattached to said housing in communication with said controller, saidcontroller having memory and configured to, upon actuation of saidrecall switch, retrieve from said memory saved pressure and volume dataand output signals representative of the saved and recalled data to saiddisplay.
 8. The device as set forth in claim 1, including a selectablekey data switch attached to said housing in communication with saidcontroller, said controller having memory and configured to store insaid memory the current fluid pressure and volume data upon actuation ofsaid key data switch.
 9. The device as set forth in claim 1, wherein: acommunication module is attached to said controller for receiving outputsignals therefrom and is configured to wirelessly transmit the outputsignals to a receiver; said battery providing energy to saidcommunication module; and wherein said housing, including said reservoirand said communication module, said pump including said actuator, saidpressure sensor, said volume sensor, said controller, said display andsaid battery cumulatively have a weight of 1.5 kilograms or less. 10.The device as set forth in claim 9, wherein said communication moduleincludes an infra-red LED.
 11. The device as set forth in claim 9,wherein said housing, including said reservoir and said communicationsmodule, said pump including said actuator, said pressure sensor, saidvolume sensor, said controller, said display and said batterycumulatively have a weight of 0.5 kilograms or less.
 12. The device asset forth in claim 1 wherein said controller is configured fordetermining a composite metric based on at least two of the pressure,the volume, and time and displaying said composite metric on saiddisplay.
 13. The device as set forth in claim 1, wherein said pump iscapable of discharging fluid into said discography needle at a maximumpressure of 200 psi.
 14. The device as set forth in claim 1, whereinsaid housing, including said reservoir, said pump including saidactuator, said pressure sensor, said volume sensor, said controller,said display and said battery cumulatively have a weight of 0.5kilograms or less.
 15. The device as set forth in claim 1, wherein saiddiscography needle has a length of at least 12 cm and an outer diameterof 18 gauge or smaller.
 16. The device as set forth in claim 1 whereinsaid controller includes memory for saving data during use, said datarelating to the pressure, the volume, and time.
 17. A system fordelivering fluid to a target site during a medical procedure, monitoringselected parameters of the fluid delivered to the target site, andtransferring data related to the monitored parameters, said systemcomprising: a fluid delivery device adapted for being placed within asterile field to deliver fluid to the target site during the medicalprocedure, said device including: a housing defining a fluid chamber forstoring the fluid to be delivered to the target site; a plunger having adistal end disposed in said fluid chamber for discharging the fluid fromsaid fluid chamber to the target site during the medical procedure assaid plunger moves in said fluid chamber relative to said housing; apressure sensor for sensing a pressure of the fluid in said fluidchamber; a volume sensor for sensing a volume of the fluid dischargedfrom said fluid chamber; and a controller in communication with saidpressure sensor and said volume sensor for determining values of thepressure and the volume, said controller having memory for storing datarelated to said values of the pressure and the volume; in combinationwith: a data transfer system adapted for being placed outside of thesterile field and including an external device spaced from said fluiddelivery device and configured for wirelessly receiving said data fromsaid controller.
 18. A fluid delivery device for delivering fluid to anintervertebral disc of a patient during a discography procedure, saiddevice comprising: a housing defining a fluid chamber for storing thefluid; a plunger having a distal end disposed in said fluid chamber fordischarging the fluid from said fluid chamber to the intervertebral discduring the discography as said plunger moves in said fluid chamberrelative to said housing; a pressure sensor for sensing a pressure ofthe fluid in said fluid chamber; a physiological sensor for sensing aphysiological parameter of the patient, said physiological parameterbeing uncontrollable by the patient; a controller in communication withsaid pressure sensor and said physiological sensor for determiningvalues of the pressure and said physiological parameter, said controllerbeing configured for automatically marking a key value of the pressurein response to said value of said physiological parameter exceeding apredetermined limit wherein said predetermined limit correlates to apredetermined level of pain sensed by the patient and said value of saidphysiological parameter is unable to be controlled by the patient.